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Numerical examinations of simplified spondylodesis models concerning energy absorption in magnetic resonance imaging

  • Nicole Hadert EMAIL logo , Qi Liu and Waldemar Zylka
Published/Copyright: September 30, 2016
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Current Directions in Biomedical Engineering
From the journal Current Directions in Biomedical Engineering Volume 2 Issue 1

Abstract

Metallic implants in magnetic resonance imaging (MRI) are a potential safety risk since the energy absorption may increase temperature of the surrounding tissue. The temperature rise is highly dependent on implant size. Numerical examinations can be used to calculate the energy absorption in terms of the specific absorption rate (SAR) induced by MRI on orthopaedic implants. This research presents the impact of titanium osteosynthesis spine implants, called spondylodesis, deduced by numerical examinations of energy absorption in simplified spondylodesis models placed in 1.5 T and 3.0 T MRI body coils. The implants are modelled along with a spine model consisting of vertebrae and disci intervertebrales thus extending previous investigations [1], [2]. Increased SAR values are observed at the ends of long implants, while at the center SAR is significantly lower. Sufficiently short implants show increased SAR along the complete length of the implant. A careful data analysis reveals that the particular anatomy, i.e. vertebrae and disci intervertebrales, has a significant effect on SAR. On top of SAR profile due to the implant length, considerable SAR variations at small scale are observed, e.g. SAR values at vertebra are higher than at disc positions.

Keywords: SAR; MRI; osteosynthesis implants; numerical simulation

1 Introduction

MRI is considered as a secure imaging method in medical diagnosis [3]. However the electromagnetic fields might be safety hazards for the human body. Particularly the energy of the high frequency field B1 might by absorbed by metallic structures like implants. The absorbed energy is converted to heat resulting in potential temperature increase of tissue [4]. In medical application the body tissue temperature should not increase more than 1°C. It approximately corresponds to SAR = 4 W/kg in whole body or, dependent on region, SAR = 4–10 W/kg dependent on the body weight. Temperature of 43°C or more causes tissue injury [4], [5]. MRI examinations on patients with metallic implants are at discretion of medical professions and associated with individual risk.

Numerical modelling and simulation is a technique to access the impact of B1 field on SAR and temperature. Only very few studies investigate numerical modelling of orthopedic implants. For an implant consisting of a rod with pins at its ends and placed in aqueous gel increasing SAR is observed at the ends of a conductive bar [1]. For external fixation device SAR depends on pin spacing and insertion depth (into the gel) [2]. In both studies spine is not modeled. This research focuses on the calculation of energy absorption of different simplified models of spondylodesis exposed to B1 field. Spondylodesis is an implant where concerned spine segments are fixed with screw-rod-system. Thus, all models explicitly include vertebrae and disci intervertebrales.

2 Methods

Numerical examinations of energy absorption via MRI simulations are executed with the software Electromagnetic Suite 15 from ANSYS, Inc. Various models of MRI body coils, spine and spondylodesis implants have been developed and examined for 1.5 T/64 MHz and 3 T/128 MHz.

2.1 MRI coil models and SAR

The high frequency field of the MRI body coil model for 1.5 T MRI calculations is generated by a quadrature birdcage coil [6]. The high frequency field for the 3 T MRI simulations is generated by a model of a multi-transmit coil. It divides the B1 field into separate B1 subfields by using the ports as independent power supply channels. The induced electrical field is Emax = 90 V/m. Both body coils (1.5 T and 3 T) are cylinders with height h = 650 mm and diameter d = 620 mm (Figure 1). Inside the quadrature coil an almost homogeneous magnetic field B1 = 1.4 μT is generated. Inside the multi-transmit coil an almost homogeneous magnetic field B1 = 1.5 μT is generated.

Figure 1 Model of MRI body coil with RF shield.
Figure 1

Model of MRI body coil with RF shield.

Electromagnetic fields are calculated by solving Maxwell equations. For SAR calculation first the particular tissue densities and local SAR in finite elements must be determined. Then the SAR algorithm runs on voxels, which are generated from finite elements [8]. Local SAR is defined as the dissipated power Pdiss per mass m at the point r. It depends on intensity of the induced electrical field E and specific electrical conductivity σ of tissue and its density ρ.

S⁢A⁢R⁢(𝒓)=1V⁢∫VPd⁢i⁢s⁢sm⁢d⁢V=1V⁢∫Vσ⁢(𝒓)2⁢ρ⁢(𝒓)⁢|𝑬⁢(𝒓)|2⁢d⁢V

It is specified by international safety norm IEC 606012-33 [9]. Here we use m = 10 g. Along with the tissue density this mass defines a volume V around this tissue point. Specific physical and electrical parameters, mass density, conductivity, permittivity, and permeability of each tissue or material of the model has to be set. Values can be found in literature, e.g. [10], [11].

2.2 Spondylodesis models

The torso phantom is a plexiglas body filled with liquid. The electromagnetic parameters of liquid are similar to those of tissue [6]. Its electrical conductivity is σ = 0.47 (Ωm)−1 and relative permittivity ϵr = 81 F/m. The torso phantom is placed in the body coil in order to represent a human torso lying on his back in the MRI.

Simplified models for multi-vertebrae sections of spine are developed and combined with a simplified model of osteosynthesis spine implants:

  1. a two vertebrae model and a nine vertebrae model concentrated on the ventral static support motion elements of spine

  2. a small spondylodesis over two vertebrae and a large spondylodesis over nine vertebrae

  3. additionally two vertebrae positioned at both edges of the spondylodesis models (only for 1.5 T MRI)

The simplified spondylodesis model concentrates on the ventral static support of the movement elements of spine. The blue discs represent disci intervertebrales, the white-grey cylinder medulla spinalis, the brown cylinders corpus vertebrae and foramen vertebrae and the grey rods represent screws and frame rods of the implant (Figure 2). The spondylodesis model consists of six or twenty titanium rods. Two rods along multi-vertebrae as frame rods with length l2 = 23.3 mm, l9 = 116.4 mm and diameter d = 2 mm and four or eighteen rods with tip orthogonal to the frame rods as screws with length l = 13.33 mm and diameter d = 1 mm.

Figure 2 Top: Simplified spondylodesis model, the description is given in the main text. Bottom: Part of torso phantom with imbedded large spondylodesis over nine vertebrae, positions of vertebrae in Table 1. The red line indicates layer where SAR profiles are examined.
Figure 2

Top: Simplified spondylodesis model, the description is given in the main text. Bottom: Part of torso phantom with imbedded large spondylodesis over nine vertebrae, positions of vertebrae in Table 1. The red line indicates layer where SAR profiles are examined.

Table 1:

Positions of vertebrae in torso phantom.

ModelPosition [mm]
DistalProximal
2 vertebrae141.7–151.7155–165
9 vertebrae48.6–58.6155–165

3 Results

The electromagnetic fields are examined in direction of the coil axis. In the empty coil the electrical field decreases linear to its minimum at the center and then increases with same gradient value. In vertebrae models along the coil axis the electrical field shows the posterior shape of vertebrae and spinal discs with high values at vertebrae and low values at spinal discs. In spondylodesis models this structure is still visible but with decreasing trend from distal to the model center and increasing to proximal (Figure 3).

Figure 3 Medial layer of electrical fields examined in direction of the coil axis. Top: Dashed line indicates electrical field in empty coil and black line in two vertebrae model. Scale of amplitude [0, 140] V/m and distance [0, 325] mm. Bottom: Black line indicates electrical field in nine vertebrae model and dashed line in nine vertebrae spondylodesis model. Scale of amplitude [0, 250] V/m and distance [0, 325] mm.
Figure 3

Medial layer of electrical fields examined in direction of the coil axis. Top: Dashed line indicates electrical field in empty coil and black line in two vertebrae model. Scale of amplitude [0, 140] V/m and distance [0, 325] mm. Bottom: Black line indicates electrical field in nine vertebrae model and dashed line in nine vertebrae spondylodesis model. Scale of amplitude [0, 250] V/m and distance [0, 325] mm.

The SAR is examined in direction of the posterior sagittal spine layer between bones and tissue (Figure 2). Along the implant SAR hotspots appear near the titanium rod edges and spread posterior between implants and MRI table (Figure 4). Between bones and tissue the SAR describes positions of vertebrae and disci intervertebrales. Maximum values are detected at vertebrae and minimum values at disci intervertebrales. Towards the model center values decrease (Figures 4–6). The SAR profile in spondylodesis models with additional vertebrae shows hotspots at vertebrae positions near rod edges with a slight decrease to the outer vertebrae, indicated as blue lines in Figure 5. Compared to the spondylodesis model without additional vertebrae in Figure 6 the maximum intensity is lower.

Figure 4 SAR in medial implant layer in 1.5 T MRI. SAR hotspots at rod edges spread posterior between implants and MRI table. SAR [0.01, 4.6] W/kg.
Figure 4

SAR in medial implant layer in 1.5 T MRI. SAR hotspots at rod edges spread posterior between implants and MRI table. SAR [0.01, 4.6] W/kg.

Figure 5 SAR profile in posterior layer between bones and tissue in 1.5 T MRI. Spondylodesis models are indicated as black line and models with additional vertebrae as blue line. Spondylodesis models with additional vertebrae are shown as an overlay to indicate the position for SAR variations. Top plot: models of small implant over two vertebrae. Scale of SAR [0, 1] W/kg and distance [0,325] mm. Bottom plot: models of large implant over nine vertebrae. Scale of SAR [0, 4.5] W/kg and distance [0, 325] mm.
Figure 5

SAR profile in posterior layer between bones and tissue in 1.5 T MRI. Spondylodesis models are indicated as black line and models with additional vertebrae as blue line. Spondylodesis models with additional vertebrae are shown as an overlay to indicate the position for SAR variations. Top plot: models of small implant over two vertebrae. Scale of SAR [0, 1] W/kg and distance [0,325] mm. Bottom plot: models of large implant over nine vertebrae. Scale of SAR [0, 4.5] W/kg and distance [0, 325] mm.

Figure 6 SAR profile in posterior layer between bones and tissue in spondylodesis models in 1.5 T MRI indicated as black line and 3 T MRI as blue line. Spondylodesis models are shown as an overlay to indicate the position for SAR variations. Top plot: models of small implant over two vertebrae. Scale of SAR [0, 4] W/kg and distance [0, 325] mm. Bottom plot: models of large implant over nine vertebrae. Scale of SAR [0, 6] W/kg and distance [0, 325] mm.
Figure 6

SAR profile in posterior layer between bones and tissue in spondylodesis models in 1.5 T MRI indicated as black line and 3 T MRI as blue line. Spondylodesis models are shown as an overlay to indicate the position for SAR variations. Top plot: models of small implant over two vertebrae. Scale of SAR [0, 4] W/kg and distance [0, 325] mm. Bottom plot: models of large implant over nine vertebrae. Scale of SAR [0, 6] W/kg and distance [0, 325] mm.

4 Discussion and conclusion

SAR values in 1.5 T MRI are up to 600% higher with implant models than without [12]. Values in Table 2 distinguish the large scale variations due to the impact of implant size. In the spondylodesis model over nine vertebrae in 1.5 T SAR varies about 840% and in 3 T about 255%. The multiplyer of SAR in spondylodesis models over two vertebrae between 1.5 T and 3 T is five.

Table 2:

SAR Hotspots near titanium rod edges at distal vertebrae, proximal vertebrae and extinction in model centers. All values are in [W/kg].

LayerModelSARdisSARproxSARmin
1.5 T MRI
Between bones2 vertebrae0.680.690.2
and tissue9 vertebrae2.554.20.05
2 additional vertebrae at implant edges
Between bones2 vertebrae0.90.9050.55
and tissue9 vertebrae3.553.80.1
3 T MRI
Between bones2 vertebrae3.63.82.45
and tissue9 vertebrae2.95.10.2

The results shown in Figures 5 and 6 approve the global pattern that energy deposition is related to the implant size [2]. SAR hotspots appear at implant edges and with sufficient rod length, here over nine vertebrae, extinction to the model center occures (Figures 4–6). Figure 3 compared to Figures 5 and 6 show that extinction in SAR relates to electrical field profile in spondylodesis models. Further more the results lead to conclusion that energy absorption depends on bone and tissue geometry, since the SAR profile between bones and tissue describes positions of vertebrae and disci intervertebrales with high values at vertebrae and low values at disci intervertebrales similar to the electrical field profile. Due to the fact that bone influences electrical fields the spine model needs to be enhanced.

Author’s Statement

Research funding: The author state no funding involved. Conflict of interest: Authors state no conflict of interest. Material and Methods: Informed consent: Informed consent is not applicable. Ethical approval: The conducted research is not related to either human or animals use.

References

[1] Liu Y, Chen Y, Shellock F, Kainz W. Computational and experimental studies of an orthopedic implant: MRI-related heating at 1.5-T/64-MHz and 3-T/128-MHz. J Magn Reson Imaging. 2013;37:491–7.10.1002/jmri.23764Search in Google Scholar PubMed

[2] Liu Y, Shen J, Kainz W, Qian S, Wu W, Chen J. Numerical investigations of MRI RF field induced heating for external fixation devices. Biomed Eng Online. 2013;12:12.10.1186/1475-925X-12-12Search in Google Scholar PubMed PubMed Central

[3] Frese G. Vorschriften und Normen zur MR Sicherheit. Siemens Medical Solutions; 2004.Search in Google Scholar

[4] Nitz WR. Praxiskurs MRT. Georg Thieme Verlag; 2011.10.1055/b-004-134432Search in Google Scholar

[5] National Institute of Health. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3729307/ (Accessed: 20.04.2016).Search in Google Scholar

[6] Stenschke J, Li D, Thomann M, Schaefers G, Zylka W. A numerical investigation of RF heating effects on implants during MRI compared to experimental measurements. Springer Proceedings in Physics. Advances in Medical Engineering, Springer; 2007. p. 53–58.10.1007/978-3-540-68764-1_8Search in Google Scholar

[7] Smajic-Peimann S, Zylka W. Simulation of SAR and temperature distributions for human organs with two different Birdcage designs at 42,6MHz and 127,8MHz. Biomed Tech. 2010;55.Search in Google Scholar

[8] ANSYS HFSS, Online Help, ANSYS; 2014.Search in Google Scholar

[9] International Electrotechnical Commission. Available at: https://webstore.iec.ch/preview/info_iec60601-2-33%7Bed3.1%7Db.pdf (Accessed: 20.04.2016).Search in Google Scholar

[10] Gabriel C, Gabriel S, Corthout E. The dielectric properties of biological tissues: I. Literature survey. Phys Med Biol. 1996;41 :2231–49.10.1088/0031-9155/41/11/001Search in Google Scholar PubMed

[11] Gabriel S, Lau RW, Gabriel C. The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues. Phys Med Biol. 1996;41:2271–93.10.1088/0031-9155/41/11/003Search in Google Scholar PubMed

[12] Hadert N, Zylka W. Numerical examinations of energy absorption in simplified spondylodesis models. YRA - Young Researchers Academy MedTech in NRW; 2016. DOI: 10.17185/duepublico/40821.Search in Google Scholar

Published Online: 2016-9-30
Published in Print: 2016-9-1

©2016 Nicole Hadert et al., licensee De Gruyter.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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https://doi.org/10.1515/cdbme-2016-0143
Keywords for this article
SAR; MRI; osteosynthesis implants; numerical simulation
Creative Commons
BY-NC-ND 4.0

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  55. Preprocessing of unipolar signals acquired by a novel intracardiac mapping system
  56. In-vitro experiments to characterize ventricular electromechanics
  57. Continuous non-invasive monitoring of blood pressure in the operating room: a cuffless optical technology at the fingertip
  58. Application of microwave sensor technology in cardiovascular disease for plaque detection
  59. Artificial blood circulatory and special Ultrasound Doppler probes for detecting and sizing gaseous embolism
  60. Detection of microsleep events in a car driving simulation study using electrocardiographic features
  61. A method to determine the kink resistance of stents and stent delivery systems according to international standards
  62. Comparison of stented bifurcation and straight vessel 3D-simulation with a prior simulated velocity profile inlet
  63. Transient Euler-Lagrange/DEM simulation of stent thrombosis
  64. Automated control of the laser welding process of heart valve scaffolds
  65. Automation of a test bench for accessing the bendability of electrospun vascular grafts
  66. Influence of storage conditions on the release of growth factors in platelet-rich blood derivatives
  67. Cryopreservation of cells using defined serum-free cryoprotective agents
  68. New bioreactor vessel for tissue engineering of human nasal septal chondrocytes
  69. Determination of the membrane hydraulic permeability of MSCs
  70. Climate retainment in carbon dioxide incubators
  71. Multiple factors influencing OR ventilation system effectiveness
  72. Evaluation of an app-based stress protocol
  73. Medication process in Styrian hospitals
  74. Control tower to surgical theater
  75. Development of a skull phantom for the assessment of implant X-ray visibility
  76. Surgical navigation with QR codes
  77. Investigation of the pressure gradient of embolic protection devices
  78. Computer assistance in femoral derotation osteotomy: a bottom-up approach
  79. Automatic depth scanning system for 3D infrared thermography
  80. A service for monitoring the quality of intraoperative cone beam CT images
  81. Resectoscope with an easy to use twist mechanism for improved handling
  82. In vitro simulation of distribution processes following intramuscular injection
  83. Adjusting inkjet printhead parameters to deposit drugs into micro-sized reservoirs
  84. A flexible standalone system with integrated sensor feedback for multi-pad electrode FES of the hand
  85. Smart control for functional electrical stimulation with optimal pulse intensity
  86. Tactile display on the remaining hand for unilateral hand amputees
  87. Effects of sustained electrical stimulation on spasticity assessed by the pendulum test
  88. An improved tracking framework for ultrasound probe localization in image-guided radiosurgery
  89. Improvement of a subviral particle tracker by the use of a LAP-Kalman-algorithm
  90. Learning discriminative classification models for grading anal intraepithelial neoplasia
  91. Regularization of EIT reconstruction based on multi-scales wavelet transforms
  92. Assessing MRI susceptibility artefact through an indicator of image distortion
  93. EyeGuidance – a computer controlled system to guide eye movements
  94. A framework for feedback-based segmentation of 3D image stacks
  95. Doppler optical coherence tomography as a promising tool for detecting fluid in the human middle ear
  96. 3D Local in vivo Environment (LivE) imaging for single cell protein analysis of bone tissue
  97. Inside-Out access strategy using new trans-vascular catheter approach
  98. US/MRI fusion with new optical tracking and marker approach for interventional procedures inside the MRI suite
  99. Impact of different registration methods in MEG source analysis
  100. 3D segmentation of thyroid ultrasound images using active contours
  101. Designing a compact MRI motion phantom
  102. Cerebral cortex classification by conditional random fields applied to intraoperative thermal imaging
  103. Classification of indirect immunofluorescence images using thresholded local binary count features
  104. Analysis of muscle fatigue conditions using time-frequency images and GLCM features
  105. Numerical evaluation of image parameters of ETR-1
  106. Fabrication of a compliant phantom of the human aortic arch for use in Particle Image Velocimetry (PIV) experimentation
  107. Effect of the number of electrodes on the reconstructed lung shape in electrical impedance tomography
  108. Hardware dependencies of GPU-accelerated beamformer performances for microwave breast cancer detection
  109. Computer assisted assessment of progressing osteoradionecrosis of the jaw for clinical diagnosis and treatment
  110. Evaluation of reconstruction parameters of electrical impedance tomography on aorta detection during saline bolus injection
  111. Evaluation of open-source software for the lung segmentation
  112. Automatic determination of lung features of CF patients in CT scans
  113. Image analysis of self-organized multicellular patterns
  114. Effect of key parameters on synthesis of superparamagnetic nanoparticles (SPIONs)
  115. Radiopacity assessment of neurovascular implants
  116. Development of a desiccant based dielectric for monitoring humidity conditions in miniaturized hermetic implantable packages
  117. Development of an artifact-free aneurysm clip
  118. Enhancing the regeneration of bone defects by alkalizing the peri-implant zone – an in vitro approach
  119. Rapid prototyping of replica knee implants for in vitro testing
  120. Protecting ultra- and hyperhydrophilic implant surfaces in dry state from loss of wettability
  121. Advanced wettability analysis of implant surfaces
  122. Patient-specific hip prostheses designed by surgeons
  123. Plasma treatment on novel carbon fiber reinforced PEEK cages to enhance bioactivity
  124. Wear of a total intervertebral disc prosthesis
  125. Digital health and digital biomarkers – enabling value chains on health data
  126. Usability in the lifecycle of medical software development
  127. Influence of different test gases in a non-destructive 100% quality control system for medical devices
  128. Device development guided by user satisfaction survey on auricular vagus nerve stimulation
  129. Empirical assessment of the time course of innovation in biomedical engineering: first results of a comparative approach
  130. Effect of left atrial hypertrophy on P-wave morphology in a computational model
  131. Simulation of intracardiac electrograms around acute ablation lesions
  132. Parametrization of activation based cardiac electrophysiology models using bidomain model simulations
  133. Assessment of nasal resistance using computational fluid dynamics
  134. Resistance in a non-linear autoregressive model of pulmonary mechanics
  135. Inspiratory and expiratory elastance in a non-linear autoregressive model of pulmonary mechanics
  136. Determination of regional lung function in cystic fibrosis using electrical impedance tomography
  137. Development of parietal bone surrogates for parietal graft lift training
  138. Numerical simulation of mechanically stimulated bone remodelling
  139. Conversion of engineering stresses to Cauchy stresses in tensile and compression tests of thermoplastic polymers
  140. Numerical examinations of simplified spondylodesis models concerning energy absorption in magnetic resonance imaging
  141. Principle study on the signal connection at transabdominal fetal pulse oximetry
  142. Influence of Siluron® insertion on model drug distribution in the simulated vitreous body
  143. Evaluating different approaches to identify a three parameter gas exchange model
  144. Effects of fibrosis on the extracellular potential based on 3D reconstructions from histological sections of heart tissue
  145. From imaging to hemodynamics – how reconstruction kernels influence the blood flow predictions in intracranial aneurysms
  146. Flow optimised design of a novel point-of-care diagnostic device for the detection of disease specific biomarkers
  147. Improved FPGA controlled artificial vascular system for plethysmographic measurements
  148. Minimally spaced electrode positions for multi-functional chest sensors: ECG and respiratory signal estimation
  149. Automated detection of alveolar arches for nasoalveolar molding in cleft lip and palate treatment
  150. Control scheme selection in human-machine- interfaces by analysis of activity signals
  151. Event-based sampling for reducing communication load in realtime human motion analysis by wireless inertial sensor networks
  152. Automatic pairing of inertial sensors to lower limb segments – a plug-and-play approach
  153. Contactless respiratory monitoring system for magnetic resonance imaging applications using a laser range sensor
  154. Interactive monitoring system for visual respiratory biofeedback
  155. Development of a low-cost senor based aid for visually impaired people
  156. Patient assistive system for the shoulder joint
  157. A passive beating heart setup for interventional cardiology training
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